Percutaneous facet fixation system

ABSTRACT

Percutaneous facet fixation implants. In some embodiments, the implant may comprise fasteners and/or fastener portions configured to be coupled on opposite sides of a facet joint such that a portion of one fastener is configured to be positioned adjacent to one of a superior articular process and an inferior articular process of a facet joint and a portion of another fastener is configured to be positioned adjacent to one of the other of an inferior articular process and a superior articular process of the facet joint so as to engage a surface of the respective articular process. In some embodiments, one or both of the fasteners may be configured to couple with an arm of a facet gun instrument.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 12/550,017 titled “PERCUTANEOUS FACET FIXATION SYSTEM” filed on Aug. 28, 2009, which application is a continuation of U.S. Pat. No. 7,608,094 issued on Oct. 27, 2009 and also titled “PERCUTANEOUS FACET FIXATION SYSTEM,” which claims priority from U.S. Provisional Patent Application Ser. No. 60/417,543, filed Oct. 10, 2002. Each of the foregoing applications is hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to spine surgery and, in particular, to a percutaneous facet fixation system.

BACKGROUND OF THE INVENTION

For patients with a high degree of spinal instability (e.g. fractures), or in revision surgery, a combination anterior/posterior fusion is indicated at one or more levels. Fusing both the front and back provides a high degree of stability for the spine and a large surface area for the bone fusion to occur. The disc may be approached either as an anterior lumbar interbody fusion (ALIF), or as a posterior lumbar interbody fusion (PLIF). Both procedures are well known to those of skill in the art.

To further stabilize vertebral segments, posterior instrumentation is often performed in conjunction with an interbody fusion. The most commonly used posterior instrumentation system in use today is pedicle screw fixation. The major disadvantage to this technique is the necessity of major muscle dissection, which can lead to morbidity and scarring.

Facet screw fixation offers the advantage of placing a single screw across each articulating facet joint to immobilize a motion segment, thereby reducing the amount of hardware (and therefore exposure) necessary. Existing techniques, however, still demand relatively open procedures, such that the need remains for a facet fixation system compatible with minimally invasive surgical (MIS) procedures.

SUMMARY OF THE INVENTION

The present invention is a percutaneous system of facet fixation that is minimally invasive, reproducible, efficient, and effective. Capable of immediate stabilization of a facet joint complex, the instrumentation and methods may be used with C-arm and/or endoscopic visualization.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a highly-simplified drawing that shows the facet joints of a patient to which this invention is applicable;

FIG. 2 is a drawing showing a posterior approach to the spine using retractors and removal of the spinous process to the junction to the lamina;

FIG. 3 is a drawing that shows a guide wire passed by C-arm or endoscopic guidance to a facet joint in conjunction with the lower arm of the facet gun;

FIG. 4 is a drawing that shows the upper arm of the facet gun, including a locking nut, inserted along the track of the guide wire of FIG. 3;

FIG. 5 shows the handle of a facet gun compressed, locking the nuts onto the upper and lower surfaces of the facet joint;

FIG. 6 shows how a bolt is driven through the superficial and deep nuts, thereby fusing the facet joint;

FIG. 7 shows the fused joint with the lower arm of the facet gun still in position;

FIG. 8 shows the removal of the lower arm;

FIG. 9 shows an alternative embodiment of a nut applicable to the invention, including fixation spikes;

FIG. 10 shows the use of a washer according to the invention, which may be wedge-shaped and which may use fixation spikes;

FIG. 11 is a drawing that shows the way in which a bolt head seats inside of a top nut through a click lock; and

FIG. 12 is a drawing of a bolt including a drill bit tab useful to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to the drawings, wherein FIG. 1 is a highly-simplified drawing that shows the facet joints 102, 102′ of a patient 100 to which this invention is applicable. The proximal spinous process is indicated at 104. The patient is placed in a prone position under general anesthetic. A C-arm is preferably utilized to determine fixation level and approach for incision.

A 1.0-inch incision 101 (or thereabouts) is made in midline over the proximal spinous process 104. (For L4-L5 fixation, the incision made over L4 spinous process.) As shown in FIG. 2, the spinous process removed to junction of lamina, allowing access angle to facet joints bilaterally.

FIG. 3 is a drawing that shows the way in which a guide wire 312 is passed by C-arm or endoscopic guidance to a facet joint in conjunction with the lower arm of a facet gun 306 according to the invention. The lower arm of facet gun 306 contains a deep locking nut 308 abutting lateral surface of the superior facet (L5). The deep locking nut 308 is positioned in alignment with the guide wire 312 by C-arm past the facet joint.

FIG. 4 is a drawing that shows the upper arm 310 of the facet gun, including a locking nut 408, also inserted along the track of the guide wire of FIG. 3. The superficial locking nut 408 is inserted over the guide sleeve of lower arm, making contact with surface of inferior facet. As shown in FIG. 5, the handle of the facet gun compressed, holding the nuts 408, 308 onto upper and under surface of facet joint.

Referring to FIG. 6, a previously selected facet bolt, preferably with drill bit head 998 as shown in FIG. 12, is inserted into barrel of upper facet gun sleeve. The bolt is driven through superficial and deep nuts using a manually operated tool 606, passing through facet joint, locking into the superficial nut and compressing the joint together.

The upper arm of facet gun is disengaged in FIG. 7. The lower arm is pushed deeper, disengaging itself from the deep nut, and the arm and guide wire are removed as shown in FIG. 8. The procedure is then repeated for opposite side.

FIG. 9 is a drawing that shows an alternative nut useful in conjunction with the invention, including an optional wedge-shape and, independent of that, the use of fixation spikes 990 operative to dig into the bone, particularly during and after compression of the joint. FIG. 10 shows how the upper nut, in particular, may be replaced with a washer 992 devoid of threads. Optionally, as with the lower locking nut, the shape of the washer in FIG. 10 may be wedge-shaped or contoured to match the facet surface, and may include optional fixation spikes as well. FIG. 11 shows the way in which a bolt head 994 may seat inside of the top nut 996, and locking in position with click stops (not visible in the picture). 

1. An implant for fusing a facet joint, comprising: a first fastener portion; and a second fastener portion configured to be connected with the first fastener portion on opposite sides of a facet joint such that a portion of the first fastener portion is configured to be positioned adjacent to one of a superior articular process and an inferior articular process of the facet joint and a portion of the second fastener portion is configured to be positioned adjacent to one of the other of an inferior articular process and a superior articular process of the facet joint so as to engage a surface of the respective articular process, and wherein a surface of at least one of the first and second fastener portions, in an unassembled configuration, is contoured to match a surface of one of the inferior articular process and the superior articular process.
 2. The implant of claim 1, wherein the first fastener portion comprises a head.
 3. The implant of claim 2, wherein the first fastener portion further comprises a first washer, wherein the head of the first fastener portion is configured to be received in the first washer in an assembled configuration, and wherein a bottom surface of the first washer, in an unassembled configuration, is contoured to match a surface of one of the inferior articular process and the superior articular process.
 4. The implant of claim 3, wherein the first washer comprises an unthreaded washer.
 5. The implant of claim 3, wherein the first washer comprises a plurality of fixation spikes.
 6. The implant of claim 1, wherein the first fastener portion comprises a facet bolt.
 7. The implant of claim 6, wherein the second fastener portion comprises a deep locking nut.
 8. The implant of claim 1, further comprising a facet bolt.
 9. The implant of claim 8, wherein the facet bolt is configured to couple the first fastener portion with the second fastener portion.
 10. The implant of claim 1, wherein the second fastener portion comprises a plurality of bone fixation spikes.
 11. The implant of claim 1, wherein a surface of each of the first and second fastener portions, in an unassembled configuration, is contoured to match a surface of one of the inferior articular process and the superior articular process.
 12. An implant for fusing a facet joint, comprising: a first fastener configured to be coupled with a first arm of a facet gun; a second fastener configured to be coupled with a second arm of the facet gun; and a facet bolt configured to couple with the first and second fasteners, wherein the facet bolt is configured to receive a guidewire therethrough, and wherein the facet bolt is further configured to couple the first and second fasteners on opposite sides of a facet joint such that the first fastener is configured to be positioned adjacent to one of a superior articular process and an inferior articular process of a facet joint and the second fastener is configured to be positioned adjacent to one of the other of an inferior articular process and a superior articular process of the facet joint so as to engage a surface of the respective articular process.
 13. The implant of claim 12, wherein the facet bolt comprises a head and a shaft.
 14. The implant of claim 12, wherein the first and second fasteners each comprise at least one of a nut and a washer.
 15. The implant of claim 12, wherein at least one of the first and second fasteners comprises an integral portion of the facet bolt.
 16. The implant of claim 12, wherein a surface of at least one of the first and second fasteners, in an unassembled configuration, is contoured to match a surface of one of the inferior articular process and the superior articular process
 17. The implant of claim 16, wherein a surface of each of the first and second fasteners, in an unassembled configuration, is contoured to match a surface of one of the inferior articular process and the superior articular process.
 18. The implant of claim 12, further comprising a first washer configured to engage a surface of one of the inferior articular process and the superior articular process on a first surface of the first washer, wherein the first washer is configured to engage at least one of the first and second fasteners on a second surface of the first washer opposite from the first surface.
 19. The implant of claim 12, wherein at least one of the first and second fasteners is at least substantially wedge-shaped.
 20. The implant of claim 12, wherein both of the first and second fasteners are at least substantially wedge-shaped. 